Android-based Home Door Locks Application via
Bluetooth for Disabled People
N.H. Ismail, Zarina Tukiran,N.N. Shamsuddin,
Faculty of Electrical and Electronic Engineering
Universiti Tun Hussein Onn Malaysia
Johor, Malaysia
{nhuda, zarin}@uthm.edu.my, [email protected]
E.I.S Saadon
Pusat Pengajian Diploma,
Universiti Tun Hussein Onn Malaysia
Johor, Malaysia
Abstract— This paper discusses about an ongoing project that
serves the needs of people with physical disabilities at home. It uses
the Bluetooth technology to establish communication between
user’s Smartphone and controller board. The prototype support
manual controlling and microcontroller controlling to lock and
unlock home door. By connecting the circuit with a relay board
and connection to the Arduino controller board it can be
controlled by a Bluetooth available to provide remote access from
tablet or smartphone. This paper addresses the development and
the functionality of the Android-based application (Android app)
to assist disabled people gain control of their living area.
Index Terms— Bluetooth, Arduino controller
I. INTRODUCTION
In Malaysia, the number of disabled people keeps increasing
year by year probably because of two common factors. Some are
born this way while others have unfortunate accidents.
According to the statistics from the Department of Social
Welfare, the total number of disabled people in Malaysia in
December 2012 is 305640. Among them, 27,363 are visual,
39,303 hearing, 180 speech, 106,252 physical, 117,699 learning,
2,130 mental and 12,713 multiple disabled people [1].
According to [2], disabled people have a limited ability to
control electrical and electronics devices (On and OFF) at their
home because normally the switches are placed at a height of
15m while the comfortable height for a wheelchair user is up to
13m only. It is also mentioned that the number of disabled-
friendly facilities in Malaysia are still minimum. Therefore,
providing a very practical facility that can ease accessing home
appliances is really required which can greatly improve the lives
of the disabled.
Recently, lot of researches have been devoted to a
technology-based home security and automation. Smart Key
Door with Wireless Security System using RF Signal [3] and
Door Locking System using RFID Technology [4] using
different mechanism to lock and unlock the door namely RF
identification card (RFID). Both using PIC16F87XA as a
microcontroller. Besides that, the Main Door Security System
using SMS [5] propose the uses of Short Message Service Text
Messaging (SMS) as a mechanism to control the system via
mobile phone to lock and unlock the door. Rabbit
Microprocessor is use as a microcontroller to perform this
operation. Face Recognition Based on Auto-Switching
Magnetic Door Lock System using Microcontroller [6] use face
recognition as a mechanism to lock and unlock the door.
With the rapid development in the fields of
communication/networks and other related wireless
technologies such as RFID (Radio Frequency Identification),
UWB (Ultra Wide Band), Zigbee, NFC (Near Field
Communication) and Bluetooth enable us to develop various
kinds of wireless systems via handsets or smartphones. Research
by [7] use handset and actuator for remote operation of various
electrical devices at home. By pressing a single button on the
handset, the signal is sent through the Zigbee technology to the
actuator and subsequently switches ON/OFF the intended
device. Research [8] on the other hand, demonstrated a
handwriting recognition technology as a security tool to manage
a security of the door. Once the disabled user enter the
handwriting on the Smartphone, the door will immediately
opened after going through the process of identification by the
system. Researcher [9] develops a home automation through
Bluetooth on Android mobile device. This system allows the
user to lock and unlock a door in a short range.
Since Bluetooth has become so prevalent in mobile devices,
it was seen as a simple, low cost and secure solution for
wirelessly connecting a mobile device to a home automation
system. Therefore, this paper developed a security system by
exploiting Bluetooth as a wireless connection protocol on
Android Mobile Device to control only one electrical appliance
which is magnetic door lock. This project, however, focuses on
those who are paralyzed from the legs up to waist level, in
particularly those who use wheelchairs. The disabled user can
easily use the Graphic User Interface (GUI) application that has
been created in the Android Smartphone to lock or unlock the
magnetic door through Bluetooth Protocol. A pop-up block will
automatically appear on the screen to show the status of the door.
At the same time, a small bulb that is attached to the door will
switch “ON” once the door is opened.
In the following section of this paper explains about how
does the system work while all the analysis of the results from
this project have been described in section III. Finally, section
IV concludes the paper.
2014 IEEE International Conference on Control System, Computing and Engineering, 28 - 30 November 2014, Penang, Malaysia
978-1-4799-5685-2 ©2014 IEEE 191
II. SYSTEM DEVELOPMENT
The architecture of the proposed home door locks
application via Bluetooth technology is depicted in Fig. 1.
Fig. 1. System architecture
An Android Apps called LockIt Door is designed to allow
user choose their selection whether lock or unlock the door. The
LockIt Door Apps is developed using Eclipse software and
programmed using Java language. Fig. 2 shows its graphical
user interface (GUI) and algorithm.
Fig. 2. Android apps (a) GUI and (b) algorithm
Once wireless communication between Smartphone
Bluetooth and Bluetooth module is established through a pairing
process, user’s key selections are sent as radio frequency (RF)
signal to the main controller board installed at home.
Then, Arduino Uno controller is used to interpret key
selections and determines whether to release or not the
electromagnetic (EM) lock home door. The Arduino is
programmed with C language. It sensed the RF signal at the
input port of the controller. The relay circuit that is connected to
Arduino released the EM lock to open the door if the relay circuit
is triggered at 12V.
III. RESULTS AND ANALYSIS
Fig. 3 shows the hardware set-up for the entire project which
compose with three main parts; LockIt Door Apps on the
Smartphone, main controller board and EM lock.
Fig. 3. Hardware set-up
Fig. 4 shows the experimental setup using smartphone as
transmitter, Bluetooth module as receiver and LED as output.
Basically, signal strength is depends on Bluetooth RF
transmitted power, receiver sensitivity, and the absorption rate
of the medium. When the medium absorbs transmitted energy
higher than the signal at the receiver, it seems like the receiver
sensitivity is low, then, the connection is lost.
Fig. 4. Experimental set-up
The Bluetooth Module of BlueBee type can receive the RF
signal from 20 to 30 meter in non-obstacle environment. Due to
these, two experiments are conducted to compare with the
theoretical part.
A. Measurement set-up for different location
There are three (3) different types of measurements have
been done; (i) indoor and, (ii) outdoor with non-obstacle area
and (iii) indoor with obstacle area. As shown in Table 1, it is
found that, for indoor (obstacle and non-obstacle area), the
maximum distance that the receiver can detect the RF signal
from the Smartphone is around 15 meters in house while for
outdoor area, the maximum distance is 20 meters. In this case, it
Main Controller Board
Blu
etoo
th M
odule
Ard
uin
o U
no C
ontr
oll
er
Rel
ay C
ircu
it
Blu
etoo
th c
om
munic
atio
n
EM Lock
at Home Door
12 Volt
5 Volt
LockIt Door
Apps
on Mobile
Device
3.3 Volt
Start
1. Scan Bluetooth module
2. Create communication link
between Bluetooth devices
3. While connection is
established, sent user’s
selection to main control
board.
End
(a) (b)
Arduino controller and Bluetooth
Module Relay circuit
EM Lock
Indicator
Light LockIt Door Apps
GUI on Smartphone
Home Door
Main Controller Board
Bluetooth Module
(Blue Bee)
LED
Controller & Bluetooth Module
2014 IEEE International Conference on Control System, Computing and Engineering, 28 - 30 November 2014, Penang, Malaysia
978-1-4799-5685-2 ©2014 IEEE 192
can be said that for non-obstacle area, the system can
communicate between input and output at a distance of at least
20 m. However, the effectiveness of the system is reduced up to
20% for an obstacle area.
TABLE I. SIGNAL STRENGTH FOR DIFFERENT LOCATIONS
Reading Area Distance
(m)
Connected/
Intermittent/
Disconnected
First Indoor (non-obstacle) 5 Connected
10 Connected
15 Intermittent
20 Disconnected
25 Disconnected
30 Disconnected
Second Outdoor (non-obstacle) 5 Connected
10 Connected
15 Connected
20 Intermittent
25 Intermittent
30 Disconnected
Third Indoor (obstacle) 5 Connected
10 Connected
15 Intermittent
20 Intermittent
25 Disconnected
30 Disconnected
B. Bluetooth power strength measurement
Bluetooh power strength measurement has been done in
Electromagnetic Compatibality Center (EMC), UTHM. Based
on the data, three (3) different types of analysis can be analyzed
in terms of (i) frequency range, (ii) power strength for two
different distances and (iii) Frequency Hoping Spread Spectrum
(FHSS).
i) Frequency range. Theoretically, Bluetooth is
a wireless technology standard for exchanging data over short
distances (using short-wavelength UHF radio waves in
the ISM band from 2.4 to 2.485 GHz) from fixed and mobile
devices, and building personal area networks (PANs)
[10].Thus, from the measurement set-up as shown in Fig. 5 and
6, it is proved that the frequency range is still in the range of
Bluetooth frequency even in a different distance and condition.
Fig. 5. Bluetooth power strength for 2m
Fig. 6. Bluetooth power strength for 3m
ii) Power strength. The reading of the graph in Fig. 5 and 6
are converted from dB(µV/m) to the dBm to calculate the value
of transmitted power of Bluetooth using Eq. 1.
𝑃𝑟 = 𝐸 [𝑑𝐵 (µ𝑉
𝑚)] − 104.7 + (20 log𝑑)
where;
Pr is power strength in dB
E is level in dB(µV/m)
d is distance between Bluetooth module and antenna
Basically, the received power from Bluetooth module (Blue
Bee) is ≥4dBm which is Class 2 radio [10]. Thus, the
measurement has proved the data which is mentioned in [10]
whereby the power strength is greater than 4dBm for both
distances as illustrated in Fig 5 and 6.
iii) FHSS. Frequency hopping is the one of the most secure
modulation techniques available. Its primary responsibility is to
receive the data signal input to be transmitted and modulate it
with a carrier signal such that the modulated signal hops from
one frequency to another at the different time slots and is spread
over a wide band of frequencies. Spread spectrums spread a
signal’s power over a wider band of frequencies, for example
2014 IEEE International Conference on Control System, Computing and Engineering, 28 - 30 November 2014, Penang, Malaysia
978-1-4799-5685-2 ©2014 IEEE 193
there is a band width trade-off in order to gain signal-to-noise
performance. This contradicts the normal approach to conserve
frequency bandwidth, but the spreading process makes the data
signal much less susceptible to electrical noise and other
interference than conventional radio modulation technique.
Other transmission and electrical noise, typically narrow in
bandwidth, will only interference with a small portion of the
spread spectrum signal, resulting in a much less interference
and less errors when the receiver demodulates the signal. From
these theory, we can know that why the graph at fig. 5 and 6
have too many peak in the range from 2.4GHz to 2.48 GHz
when the Bluetooth start communicate between the Smartphone
and the Bluetooth module.
EM lock for door consists of a magnet bar, a steel plate and
mounting accessories. When current flow, they will be bonded
together strongly until the current is cut off. The relationship
between the magnetic field contribution and its source current
element is called the Biot-Savart law as written in Eq. 2.
34 r
rdlIdB
where:
dB is perpendicular both to ds (which is the direction of the
current) and to the unit vector r directed from the element to the
point P
μ0is the magnetic constant
I is steady current
dl is a vector whose magnitude is the length of the differential
element of the wire
r is the distance from the element to the point P
When electrical current flow through a conductor, a very
weak magnetic field is generated due to the positively and
negatively charge atoms. Fig. 7 shows the direction of the
magnetic field contribution follows the right hand rule illustrated
for a straight line wire.
Fig. 7. Direction of magnetic field contribution
From Eq. 2, we can see that, the current flow can produce
the electromagnetic. According to Biot-Savart’s Law when the
signal “Lock” from the Smartphone is transmitted to the
Bluetooth module, the current will flow to trigger the relay
circuit and the relay is normally close condition. In this
condition, Magnetic Door Lock will bind together. When the
signal “Unlock” is transmitted from the Smartphone, it will
trigger back the relay and the relay was in a normally open
condition, so the Magnetic Door Lock will release because no
more the current flow.
IV. CONCLUSION AND FUTURE WORKS
The goal of this study is to propose a system that can help
disabled people to open a magnetic door wirelessly using
Android smartphone. The range and security aspects were
considered through the use of Bluetooth technology that is
embedded in the mobile device. The system was able to actuate
a pin to Lock or Unlock the door from a short distance away by
just pressing a button on a smartphone. The status of the door
also has been created to make the system more complete.
In future, the LockIt Door Apps should offer assistance in
controlling more doors, windows and basic home electronic
appliances. Battery backup system should also be considered to
ensure the completeness of the system.
ACKNOWLEDGMENT
The authors would like to thank Universiti Tun Hussein Onn
Malaysia (UTHM) and Malaysia Government for the support
and sponsor of this study.
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2014 IEEE International Conference on Control System, Computing and Engineering, 28 - 30 November 2014, Penang, Malaysia
978-1-4799-5685-2 ©2014 IEEE 194
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2014 IEEE International Conference on Control System, Computing and Engineering, 28 - 30 November 2014, Penang, Malaysia
978-1-4799-5685-2 ©2014 IEEE 195